It’s difficult to tell what’s going on with Lady Gaga in this interview. Her speech has morphed into some sort of British-Australian hybrid.
http://www.youtube.com/watch?v=iICgxrDjNUI
Nicki Minaj has gone British in her music, most notably with her alter ego, Roman Zolanski. But view this video to see how long she’s able to keep up the act over one day.

Macklemore tries to make the leap toward a British accent, but doesn’t quite make it in this video.
http://www.youtube.com/watch?v=B3JTK35tkHY
Demi Lovato was actually challenged by an interviewer to do her best British impression.